package src.UF;

/**
 * 并查集
 * 森林实现
 * 基于深度优化
 */
public class UnionFind2 implements UF{

    private int[] parent;
    private int[] rank;
    public UnionFind2(int size){
        parent = new int[size];
        rank = new int[size];
        for (int i = 0; i < parent.length; i++) {
            parent[i] = i;
            rank[i] = 1;
        }
    }

    @Override
    public int getSize() {
        return parent.length;
    }

    private int find(int p){
        if (p < 0 || p >=parent.length) {
            throw new IllegalArgumentException("index out of range.");
        }
        while (p != parent[p]) {
            p = parent[p];
        }
        return p;
    }

    @Override
    public boolean isConnected(int p, int q) {
        return find(p) == find(q);
    }

    @Override
    public void unionElements(int p, int q) {
        int pRoot = find(p);
        int qRoot = find(q);
        if (pRoot == qRoot) {
            return ;
        }
        if (rank[pRoot] < rank[qRoot] ) {
            parent[pRoot] = qRoot;
        }else if (rank[qRoot] < rank[pRoot]) {
            parent[qRoot] = pRoot;
        }else{
            parent[qRoot] = pRoot;
            rank[pRoot] += 1;
        }
    }
}